Automated shift transmissions have been used in different types of motor vehicles for quite some time. The shift movements to shift the gear steps, to activate the clutches and transmission brakes, are generally executed by pressure means activated positioning cylinders.
Such shift transmissions at least partially use the supply pressure of a vehicle in which they are installed. The shift elements, meaning the main cut-off valves and, thereafter, the following shift valves, are directly supplied with either this supply pressure or system pressure, respectively, of the vehicle, or supplied with a constant operating pressure by means of pressure reduction valves, for instance. That means that the load of the shift elements, the shift timing, the shift noise, etc., cannot, or only to a lesser extent, be influenced.
Already known through DE 10 2006 040 476 A1 is a hydraulic or a pneumatic control device, for an automated shift transmission, in which the pressure is controllable in a gear shift mechanism space, designed as a pressure storage, which is positioned and installed prior to the main cut-off valve or main-cut-off valves. Hereby, prior to a shift operation, the varying pressure means requirement is estimated or a pressure drop in the system is determined by means of a pressure sensor and, depending on the pressure means requirement, one, two or several parallel main cut-off valves will be opened to satisfy this pressure means requirement. However, as the pressure means requirement is estimated, this method is not accurate or the control of the main cut-off valves happens too late because it can only happen after it is executed, measured by the pressure sensor, then the pressure drop in the system takes place. Mainly, the known method does not allow any variable matching of the supply pressure for the respective special requirements for a certain shift scenario.
In particular, in shift transmissions of the art, which is mentioned in the generic term of the claim 1 in which the main cut-off valve or main cut-off valves, respectively, are designed as 2/2 way valves due to design simplicity, a further disadvantage can be seen in the fact that the shift device for the pressure regulation, which is positioned after the main cut-off valves, can only receive an injected pressure but the pressure cannot be lowered and thus, a further optimization of the shift transmission and its functions which requires such a pressure reduction, is not possible.